1. Technical Field of the Invention
The present invention relates to direct current motors and more particularly to at least one brush carrier that allows brushes to be disconnected from a direct current motor for servicing without disturbing motor bearings.
2. Description of the Related Art
Direct current motors commonly use a brush carrier to hold brushes in their proper positions. In some motors, brush alignment is critical to motor performance because direct current feeds through brushes to commutator segments. A misalignment between brushes and commutator segments can diminish motor performance and lead to excessive motor sparking.
In some brush type direct current motors, brushes freely slide along the curvature of the commutator segments. The frictional engagement between the brushes and the commutator segments can cause brushes and commutator surfaces to wear. Moreover, brushes often freely ride over uneven commutator surfaces that promote brush vibration and motor sparking. Both conditions shorten the useful life of brushes and commutator segments.
In many cases, it is necessary to remove brushes to inspect brush and commutator surfaces for wear. In one approach, brushes are removed by disassembling brush holders. During disassembly each brush is individually removed from its respective brush holder and thereupon examined. The disadvantages of this system and others known in the art include the excessive time, skill, and expense needed to remove, inspect, and reassemble each brush and brush holder. In addition, brush removal may not necessarily ensure access to commutator surfaces and may disturb motor bearings. When motor bearings are disturbed, the motor may become unbalanced which often leads to a timely and a costly repair. Generally, great care must be taken to realign disturbed bearings, which adds to the time and the expense required to service direct current motors.
With growing commercial preferences for motors that are easy to maintain, there is demand for a brush carrier system and method that facilitates motor service and repair without compromising motor performance.
The invention provides an apparatus and a method that allow brushes to be mechanically disconnected from a motor without disturbing a bearing and other motor parts. The apparatus comprises a shaft, at least one bearing, a rotor, a stator, and a brush carrier. The bearing is located adjacent to the shaft. The rotor is interconnected with the shaft and magnetically interacts with the stator. Preferably, either the stator and/or rotor includes a winding. The brush carrier is releasably interconnected with the rotor and/or stator such that the brush carrier can be mechanically disconnected from the rotor and/or stator without disturbing the bearing and other motor parts.
An endbell having a bearing retainer is contemplated in another aspect of the invention. The endbell and bearing retainer may be a unitary or multiple piece construction that provides some shaft support. It is further envisioned that an end surface of the winding may act as a commutator surface. In this aspect, a brush directly engages a portion of the winding. Many alternative aspects of the apparatus are also envisioned and are described below.
Another aspect of the invention involves a method for inspecting a commutator surface of a motor. The method comprises the steps of providing a motor comprising a shaft, at least one bearing, a rotor, a stator, and a brush carrier; partially disconnecting the brush carrier from an endbell having at least one aperture; and then, viewing the commutator surface through the aperture. Preferably, disconnecting the brush carrier from the endbell does not disturb the bearing, and preferably, the rotor and/or the stator include at least one winding having a portion that acts as a commutator surface.
In yet another aspect of the invention, a second brush carrier is releasably interconnected to an opposite side of the rotor and/or stator from the first brush carrier. Each brush carrier can be mechanically disconnected from the rotor and/or stator without disturbing the bearings and other motor parts.
The disclosed apparatus and method provide a brush carrier that is easy to assemble and disassemble from a motor without disturbing a bearing and other motor parts. The apparatus and method easily align brushes with commutator surfaces and simplify maintenance programs. The brush carrier is compatible with many motor types besides the wave wound motor of the preferred embodiment.
These features as well as other advantages of the invention will become apparent upon consideration of the following detailed description and accompanying drawings of the embodiments of the invention described below.